1) Place binder and text on desk. 2) Do review handout - parallel line Geometry 5 November 2012 1) Place binder and text on desk. 2) Do review handout - parallel line angle relationships 3) Do back -marking corresponding congruencies

Congruent Figures For the triangles below, ∆ABC ≅ ∆PQR The notation shows congruence and correspondence. When writing congruence statements, be sure to list corresponding angles in the same order. A B C Corresponding Angles Corresponding Sides A ≅ P AB ≅ PQ B ≅ Q BC ≅ QR C ≅ R CA ≅ RP P Q R

Objective Students will explore and apply triangle sum and properties of isosceles triangles to find missing angle measures. Students will take notes, do an investigation and use think-pair-share as they solve problems. Homework due TUESDAY: 4.2, page 208: 6 – 10, 18 – 21 4.3, page 217+: Investigation 2 show all steps write the conjecture

Strategies for problem solving: 1) Mark everything you KNOW on the diagram parallel line conjectures: AIA, AEA, CA, SSIA LP and VA conjectures triangle sum conjecture 2) use COLOR to mark congruent parts, parallel lines, etc.

you may NOT assume that: lines are parallel unless they are marked or have angle measures indicating they are parallel lines ARE perpendicular unless they are marked or angle measures indicate they are pairs of angles, segments, polygons are congruent unless they are marked with information that shows you that they are

Isosceles Triangle vocabulary, pg. 206 Legs Base Angles Vertex Angle

If the base angles are congruent, do we KNOW the triangle IS ISOSCELES? converse = ? Check your notes Switch the If…. and then…. parts CONVERSE: If a triangle has two congruent angles, the it is an isosceles triangle. Demonstration-- Investigation 2- page 208

Chapter 4 Triangles Definition Triangle Sum Conjecture Term Definition Example Triangle Sum Conjecture The sum of the measures of the angles in every triangle is 1800 x + y + z = 180⁰ Isosceles triangle conjecture If a triangle is isosceles, then its base angles are congruent Converse of Isosceles Conjecture If a triangle has two congruent angles, then it is an isosceles triangle.

vocabulary Congruent– same shape AND size Similar– same shape but not necessarily same size INCLUDED ANGLE The angle between two given sides. INCLUDED SIDE The side between two given angles. included side between ⦟A and ⦟B included angle between and C A B

Practice Handout 4.1 and 4.2 1) EVERYBODY work with your group to do 4.1: # 1, 2, 3, 6, 7 and 8 AND 4.2: 1 - 5 ALL STUDENTS need to do all these problems 2) GROUP assignments Groups 1 and 5: 4.1: # 4 4.2: #6 Groups 2 and 6: 4.1: #10 4.2: #9 Groups 3 and 7: 4.1: # 11 4.2: #8 Groups 4 and 8: 4.1: # 9 4.2: #10 CHOOSE- white board or poster paper

Debrief what did you learn today? what is still confusing? what is easy?